Re: KASAN: use-after-free Read in alloc_pid

2018-04-24 Thread Eric W. Biederman 
Tetsuo Handa  writes:

> On 2018/04/10 23:33, Tetsuo Handa wrote:
>> syzbot wrote:
>>> syzbot has found reproducer for the following crash on upstream commit
>>> c18bb396d3d261ebbb4efbc05129c5d354c541e4 (Tue Apr 10 00:04:10 2018 +)
>>> Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net
>>> syzbot dashboard link:  
>>> https://syzkaller.appspot.com/bug?extid=7a1cff37dbbef9e7ba4c
>>>
>> While we are waiting for
>> 
>>   rpc_pipefs: fix double-dput()
>>   rpc_pipefs: deal with early sget() failures
>>   kernfs: deal with early sget() failures
>>   procfs: deal with early sget() failures
>>   orangefs_kill_sb(): deal with allocation failures
>>   nfsd_umount(): deal with early sget() failures
>>   nfs: avoid double-free on early sget() failures
>>   jffs2_kill_sb(): deal with failed allocations
>>   hypfs_kill_super(): deal with failed allocations
>> 
>> in 
>> https://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs.git/log/?h=for-linus
>>  ,
>> I think the patch at
>> 
>>   WARNING in kill_block_super
>>   
>> https://syzkaller.appspot.com/bug?id=588996a25a2587be2e3a54e8646728fb9cae44e7
>> 
>> is better.
>> 
>
> OK. The patch was sent to linux.git as commit 8e04944f0ea8b838.
>
> #syz fix: mm,vmscan: Allow preallocating memory for
> register_shrinker().

Sigh no fixes tag on the commit you sent to Linus, and no
cc'ing of stable.

Can you please update the stable folks that 9ee332d99e4d ("sget():
handle failures of register_shrinker()") is fixed with the commit you
just sent to Linus?

Thank you,
Eric

Re: KASAN: use-after-free Read in alloc_pid

2018-04-24 Thread Eric W. Biederman 
Tetsuo Handa  writes:

> On 2018/04/10 23:33, Tetsuo Handa wrote:
>> syzbot wrote:
>>> syzbot has found reproducer for the following crash on upstream commit
>>> c18bb396d3d261ebbb4efbc05129c5d354c541e4 (Tue Apr 10 00:04:10 2018 +)
>>> Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net
>>> syzbot dashboard link:  
>>> https://syzkaller.appspot.com/bug?extid=7a1cff37dbbef9e7ba4c
>>>
>> While we are waiting for
>> 
>>   rpc_pipefs: fix double-dput()
>>   rpc_pipefs: deal with early sget() failures
>>   kernfs: deal with early sget() failures
>>   procfs: deal with early sget() failures
>>   orangefs_kill_sb(): deal with allocation failures
>>   nfsd_umount(): deal with early sget() failures
>>   nfs: avoid double-free on early sget() failures
>>   jffs2_kill_sb(): deal with failed allocations
>>   hypfs_kill_super(): deal with failed allocations
>> 
>> in 
>> https://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs.git/log/?h=for-linus
>>  ,
>> I think the patch at
>> 
>>   WARNING in kill_block_super
>>   
>> https://syzkaller.appspot.com/bug?id=588996a25a2587be2e3a54e8646728fb9cae44e7
>> 
>> is better.
>> 
>
> OK. The patch was sent to linux.git as commit 8e04944f0ea8b838.
>
> #syz fix: mm,vmscan: Allow preallocating memory for
> register_shrinker().

Sigh no fixes tag on the commit you sent to Linus, and no
cc'ing of stable.

Can you please update the stable folks that 9ee332d99e4d ("sget():
handle failures of register_shrinker()") is fixed with the commit you
just sent to Linus?

Thank you,
Eric

Re: KASAN: use-after-free Read in alloc_pid

2018-04-21 Thread Tetsuo Handa 
On 2018/04/10 23:33, Tetsuo Handa wrote:
> syzbot wrote:
>> syzbot has found reproducer for the following crash on upstream commit
>> c18bb396d3d261ebbb4efbc05129c5d354c541e4 (Tue Apr 10 00:04:10 2018 +)
>> Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net
>> syzbot dashboard link:  
>> https://syzkaller.appspot.com/bug?extid=7a1cff37dbbef9e7ba4c
>>
> While we are waiting for
> 
>   rpc_pipefs: fix double-dput()
>   rpc_pipefs: deal with early sget() failures
>   kernfs: deal with early sget() failures
>   procfs: deal with early sget() failures
>   orangefs_kill_sb(): deal with allocation failures
>   nfsd_umount(): deal with early sget() failures
>   nfs: avoid double-free on early sget() failures
>   jffs2_kill_sb(): deal with failed allocations
>   hypfs_kill_super(): deal with failed allocations
> 
> in 
> https://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs.git/log/?h=for-linus 
> ,
> I think the patch at
> 
>   WARNING in kill_block_super
>   
> https://syzkaller.appspot.com/bug?id=588996a25a2587be2e3a54e8646728fb9cae44e7
> 
> is better.
> 

OK. The patch was sent to linux.git as commit 8e04944f0ea8b838.

#syz fix: mm,vmscan: Allow preallocating memory for register_shrinker().

Re: KASAN: use-after-free Read in alloc_pid

2018-04-21 Thread Tetsuo Handa 
On 2018/04/10 23:33, Tetsuo Handa wrote:
> syzbot wrote:
>> syzbot has found reproducer for the following crash on upstream commit
>> c18bb396d3d261ebbb4efbc05129c5d354c541e4 (Tue Apr 10 00:04:10 2018 +)
>> Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net
>> syzbot dashboard link:  
>> https://syzkaller.appspot.com/bug?extid=7a1cff37dbbef9e7ba4c
>>
> While we are waiting for
> 
>   rpc_pipefs: fix double-dput()
>   rpc_pipefs: deal with early sget() failures
>   kernfs: deal with early sget() failures
>   procfs: deal with early sget() failures
>   orangefs_kill_sb(): deal with allocation failures
>   nfsd_umount(): deal with early sget() failures
>   nfs: avoid double-free on early sget() failures
>   jffs2_kill_sb(): deal with failed allocations
>   hypfs_kill_super(): deal with failed allocations
> 
> in 
> https://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs.git/log/?h=for-linus 
> ,
> I think the patch at
> 
>   WARNING in kill_block_super
>   
> https://syzkaller.appspot.com/bug?id=588996a25a2587be2e3a54e8646728fb9cae44e7
> 
> is better.
> 

OK. The patch was sent to linux.git as commit 8e04944f0ea8b838.

#syz fix: mm,vmscan: Allow preallocating memory for register_shrinker().

Re: KASAN: use-after-free Read in alloc_pid

2018-04-10 Thread Tetsuo Handa 
syzbot wrote:
> syzbot has found reproducer for the following crash on upstream commit
> c18bb396d3d261ebbb4efbc05129c5d354c541e4 (Tue Apr 10 00:04:10 2018 +)
> Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net
> syzbot dashboard link:  
> https://syzkaller.appspot.com/bug?extid=7a1cff37dbbef9e7ba4c
> 
While we are waiting for

  rpc_pipefs: fix double-dput()
  rpc_pipefs: deal with early sget() failures
  kernfs: deal with early sget() failures
  procfs: deal with early sget() failures
  orangefs_kill_sb(): deal with allocation failures
  nfsd_umount(): deal with early sget() failures
  nfs: avoid double-free on early sget() failures
  jffs2_kill_sb(): deal with failed allocations
  hypfs_kill_super(): deal with failed allocations

in 
https://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs.git/log/?h=for-linus ,
I think the patch at

  WARNING in kill_block_super
  https://syzkaller.appspot.com/bug?id=588996a25a2587be2e3a54e8646728fb9cae44e7

is better.

Re: KASAN: use-after-free Read in alloc_pid

2018-04-10 Thread Tetsuo Handa 
syzbot wrote:
> syzbot has found reproducer for the following crash on upstream commit
> c18bb396d3d261ebbb4efbc05129c5d354c541e4 (Tue Apr 10 00:04:10 2018 +)
> Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net
> syzbot dashboard link:  
> https://syzkaller.appspot.com/bug?extid=7a1cff37dbbef9e7ba4c
> 
While we are waiting for

  rpc_pipefs: fix double-dput()
  rpc_pipefs: deal with early sget() failures
  kernfs: deal with early sget() failures
  procfs: deal with early sget() failures
  orangefs_kill_sb(): deal with allocation failures
  nfsd_umount(): deal with early sget() failures
  nfs: avoid double-free on early sget() failures
  jffs2_kill_sb(): deal with failed allocations
  hypfs_kill_super(): deal with failed allocations

in 
https://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs.git/log/?h=for-linus ,
I think the patch at

  WARNING in kill_block_super
  https://syzkaller.appspot.com/bug?id=588996a25a2587be2e3a54e8646728fb9cae44e7

is better.

Re: KASAN: use-after-free Read in alloc_pid

2018-04-10 Thread syzbot 

syzbot has found reproducer for the following crash on upstream commit
c18bb396d3d261ebbb4efbc05129c5d354c541e4 (Tue Apr 10 00:04:10 2018 +)
Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net
syzbot dashboard link:  
https://syzkaller.appspot.com/bug?extid=7a1cff37dbbef9e7ba4c


So far this crash happened 7 times on upstream.
C reproducer: https://syzkaller.appspot.com/x/repro.c?id=544516125184
syzkaller reproducer:  
https://syzkaller.appspot.com/x/repro.syz?id=5779667084640256
Raw console output:  
https://syzkaller.appspot.com/x/log.txt?id=5571293525049344
Kernel config:  
https://syzkaller.appspot.com/x/.config?id=-771321277174894814

compiler: gcc (GCC) 8.0.1 20180301 (experimental)

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+7a1cff37dbbef9e7b...@syzkaller.appspotmail.com
It will help syzbot understand when the bug is fixed.

Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS  
Google 01/01/2011

Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x1b9/0x294 lib/dump_stack.c:113
==
 fail_dump lib/fault-inject.c:51 [inline]
 should_fail.cold.4+0xa/0x1a lib/fault-inject.c:149
BUG: KASAN: use-after-free in alloc_pid+0x9e8/0xa50 kernel/pid.c:236
Read of size 4 at addr 8801ad357898 by task syzkaller392486/4543

 __should_failslab+0x124/0x180 mm/failslab.c:32
 should_failslab+0x9/0x14 mm/slab_common.c:1522
 slab_pre_alloc_hook mm/slab.h:423 [inline]
 slab_alloc mm/slab.c:3378 [inline]
 kmem_cache_alloc+0x2af/0x760 mm/slab.c:3552
 __d_alloc+0xc1/0xc00 fs/dcache.c:1624
 d_alloc+0x8e/0x370 fs/dcache.c:1702
 d_alloc_name+0xb3/0x110 fs/dcache.c:1756
 proc_setup_self+0xbe/0x375 fs/proc/self.c:43
 proc_fill_super+0x24d/0x2f5 fs/proc/inode.c:514
 mount_ns+0x12a/0x1d0 fs/super.c:1036
 proc_mount+0x73/0xa0 fs/proc/root.c:101
 mount_fs+0xae/0x328 fs/super.c:1222
 vfs_kern_mount.part.34+0xd4/0x4d0 fs/namespace.c:1037
 vfs_kern_mount fs/namespace.c:3303 [inline]
 kern_mount_data+0x50/0xc0 fs/namespace.c:3303
 pid_ns_prepare_proc+0x1e/0x90 fs/proc/root.c:222
 alloc_pid+0x8cf/0xa50 kernel/pid.c:208
 copy_process.part.38+0x36bf/0x6ee0 kernel/fork.c:1809
 copy_process kernel/fork.c:1608 [inline]
 _do_fork+0x291/0x12a0 kernel/fork.c:2089
 SYSC_clone kernel/fork.c:2196 [inline]
 SyS_clone+0x37/0x50 kernel/fork.c:2190
 do_syscall_64+0x29e/0x9d0 arch/x86/entry/common.c:287
 entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x442639
RSP: 002b:7ffd890f8138 EFLAGS: 0206 ORIG_RAX: 0038
RAX: ffda RBX: 0001 RCX: 00442639
RDX: 28c0 RSI: 2800 RDI: 2000c100
RBP: 7ffd890f8250 R08: 2940 R09: 0004
R10: 2900 R11: 0206 R12: 
R13:  R14: 1380 R15: 7ffd890f8278
CPU: 1 PID: 4543 Comm: syzkaller392486 Not tainted 4.16.0+ #17
proc_fill_super: can't allocate /proc/self
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS  
Google 01/01/2011

Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x1b9/0x294 lib/dump_stack.c:113
 print_address_description+0x6c/0x20b mm/kasan/report.c:256
 kasan_report_error mm/kasan/report.c:354 [inline]
 kasan_report.cold.7+0xac/0x2f5 mm/kasan/report.c:412
 __asan_report_load4_noabort+0x14/0x20 mm/kasan/report.c:432
 alloc_pid+0x9e8/0xa50 kernel/pid.c:236
 copy_process.part.38+0x36bf/0x6ee0 kernel/fork.c:1809
 copy_process kernel/fork.c:1608 [inline]
 _do_fork+0x291/0x12a0 kernel/fork.c:2089
 SYSC_clone kernel/fork.c:2196 [inline]
 SyS_clone+0x37/0x50 kernel/fork.c:2190
 do_syscall_64+0x29e/0x9d0 arch/x86/entry/common.c:287
 entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x442639
RSP: 002b:7ffd890f8138 EFLAGS: 0206 ORIG_RAX: 0038
RAX: ffda RBX:  RCX: 00442639
RDX: 28c0 RSI: 2800 RDI: 2000c100
RBP: 7ffd890f8250 R08: 2940 R09: 
R10: 2900 R11: 0206 R12: 
R13:  R14:  R15: 7ffd890f8278

Allocated by task 4543:
 save_stack+0x43/0xd0 mm/kasan/kasan.c:448
 set_track mm/kasan/kasan.c:460 [inline]
 kasan_kmalloc+0xc4/0xe0 mm/kasan/kasan.c:553
 kasan_slab_alloc+0x12/0x20 mm/kasan/kasan.c:490
 kmem_cache_alloc+0x12e/0x760 mm/slab.c:3554
 kmem_cache_zalloc include/linux/slab.h:691 [inline]
 create_pid_namespace kernel/pid_namespace.c:97 [inline]
 copy_pid_ns+0x2c3/0xb40 kernel/pid_namespace.c:156
 create_new_namespaces+0x48a/0x8f0 kernel/nsproxy.c:94
 copy_namespaces+0x3f7/0x4c0 kernel/nsproxy.c:165
 copy_process.part.38+0x353a/0x6ee0 kernel/fork.c:1798
 copy_process kernel/fork.c:1608 [inline]
 _do_fork+0x291/0x12a0 kernel/fork.c:2089
 SYSC_clone kernel/fork.c:2196 [inline]
 SyS_clone+0x37/0x50 kernel/fork.c:2190
 do_syscall_64+0x29e/0x9d0

Re: KASAN: use-after-free Read in alloc_pid

2018-04-10 Thread syzbot 

syzbot has found reproducer for the following crash on upstream commit
c18bb396d3d261ebbb4efbc05129c5d354c541e4 (Tue Apr 10 00:04:10 2018 +)
Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net
syzbot dashboard link:  
https://syzkaller.appspot.com/bug?extid=7a1cff37dbbef9e7ba4c


So far this crash happened 7 times on upstream.
C reproducer: https://syzkaller.appspot.com/x/repro.c?id=544516125184
syzkaller reproducer:  
https://syzkaller.appspot.com/x/repro.syz?id=5779667084640256
Raw console output:  
https://syzkaller.appspot.com/x/log.txt?id=5571293525049344
Kernel config:  
https://syzkaller.appspot.com/x/.config?id=-771321277174894814

compiler: gcc (GCC) 8.0.1 20180301 (experimental)

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+7a1cff37dbbef9e7b...@syzkaller.appspotmail.com
It will help syzbot understand when the bug is fixed.

Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS  
Google 01/01/2011

Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x1b9/0x294 lib/dump_stack.c:113
==
 fail_dump lib/fault-inject.c:51 [inline]
 should_fail.cold.4+0xa/0x1a lib/fault-inject.c:149
BUG: KASAN: use-after-free in alloc_pid+0x9e8/0xa50 kernel/pid.c:236
Read of size 4 at addr 8801ad357898 by task syzkaller392486/4543

 __should_failslab+0x124/0x180 mm/failslab.c:32
 should_failslab+0x9/0x14 mm/slab_common.c:1522
 slab_pre_alloc_hook mm/slab.h:423 [inline]
 slab_alloc mm/slab.c:3378 [inline]
 kmem_cache_alloc+0x2af/0x760 mm/slab.c:3552
 __d_alloc+0xc1/0xc00 fs/dcache.c:1624
 d_alloc+0x8e/0x370 fs/dcache.c:1702
 d_alloc_name+0xb3/0x110 fs/dcache.c:1756
 proc_setup_self+0xbe/0x375 fs/proc/self.c:43
 proc_fill_super+0x24d/0x2f5 fs/proc/inode.c:514
 mount_ns+0x12a/0x1d0 fs/super.c:1036
 proc_mount+0x73/0xa0 fs/proc/root.c:101
 mount_fs+0xae/0x328 fs/super.c:1222
 vfs_kern_mount.part.34+0xd4/0x4d0 fs/namespace.c:1037
 vfs_kern_mount fs/namespace.c:3303 [inline]
 kern_mount_data+0x50/0xc0 fs/namespace.c:3303
 pid_ns_prepare_proc+0x1e/0x90 fs/proc/root.c:222
 alloc_pid+0x8cf/0xa50 kernel/pid.c:208
 copy_process.part.38+0x36bf/0x6ee0 kernel/fork.c:1809
 copy_process kernel/fork.c:1608 [inline]
 _do_fork+0x291/0x12a0 kernel/fork.c:2089
 SYSC_clone kernel/fork.c:2196 [inline]
 SyS_clone+0x37/0x50 kernel/fork.c:2190
 do_syscall_64+0x29e/0x9d0 arch/x86/entry/common.c:287
 entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x442639
RSP: 002b:7ffd890f8138 EFLAGS: 0206 ORIG_RAX: 0038
RAX: ffda RBX: 0001 RCX: 00442639
RDX: 28c0 RSI: 2800 RDI: 2000c100
RBP: 7ffd890f8250 R08: 2940 R09: 0004
R10: 2900 R11: 0206 R12: 
R13:  R14: 1380 R15: 7ffd890f8278
CPU: 1 PID: 4543 Comm: syzkaller392486 Not tainted 4.16.0+ #17
proc_fill_super: can't allocate /proc/self
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS  
Google 01/01/2011

Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x1b9/0x294 lib/dump_stack.c:113
 print_address_description+0x6c/0x20b mm/kasan/report.c:256
 kasan_report_error mm/kasan/report.c:354 [inline]
 kasan_report.cold.7+0xac/0x2f5 mm/kasan/report.c:412
 __asan_report_load4_noabort+0x14/0x20 mm/kasan/report.c:432
 alloc_pid+0x9e8/0xa50 kernel/pid.c:236
 copy_process.part.38+0x36bf/0x6ee0 kernel/fork.c:1809
 copy_process kernel/fork.c:1608 [inline]
 _do_fork+0x291/0x12a0 kernel/fork.c:2089
 SYSC_clone kernel/fork.c:2196 [inline]
 SyS_clone+0x37/0x50 kernel/fork.c:2190
 do_syscall_64+0x29e/0x9d0 arch/x86/entry/common.c:287
 entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x442639
RSP: 002b:7ffd890f8138 EFLAGS: 0206 ORIG_RAX: 0038
RAX: ffda RBX:  RCX: 00442639
RDX: 28c0 RSI: 2800 RDI: 2000c100
RBP: 7ffd890f8250 R08: 2940 R09: 
R10: 2900 R11: 0206 R12: 
R13:  R14:  R15: 7ffd890f8278

Allocated by task 4543:
 save_stack+0x43/0xd0 mm/kasan/kasan.c:448
 set_track mm/kasan/kasan.c:460 [inline]
 kasan_kmalloc+0xc4/0xe0 mm/kasan/kasan.c:553
 kasan_slab_alloc+0x12/0x20 mm/kasan/kasan.c:490
 kmem_cache_alloc+0x12e/0x760 mm/slab.c:3554
 kmem_cache_zalloc include/linux/slab.h:691 [inline]
 create_pid_namespace kernel/pid_namespace.c:97 [inline]
 copy_pid_ns+0x2c3/0xb40 kernel/pid_namespace.c:156
 create_new_namespaces+0x48a/0x8f0 kernel/nsproxy.c:94
 copy_namespaces+0x3f7/0x4c0 kernel/nsproxy.c:165
 copy_process.part.38+0x353a/0x6ee0 kernel/fork.c:1798
 copy_process kernel/fork.c:1608 [inline]
 _do_fork+0x291/0x12a0 kernel/fork.c:2089
 SYSC_clone kernel/fork.c:2196 [inline]
 SyS_clone+0x37/0x50 kernel/fork.c:2190
 do_syscall_64+0x29e/0x9d0

Re: KASAN: use-after-free Read in alloc_pid

2018-04-03 Thread Tetsuo Handa 
On 2018/04/03 12:10, Eric Biggers wrote:
> On Mon, Apr 02, 2018 at 06:00:57PM -0500, Eric W. Biederman wrote:
>> syzbot  writes:
>>
>>> Hello,
>>>
>>> syzbot hit the following crash on upstream commit
>>> 9dd2326890d89a5179967c947dab2bab34d7ddee (Fri Mar 30 17:29:47 2018 +)
>>> Merge tag 'ceph-for-4.16-rc8' of git://github.com/ceph/ceph-client
>>> syzbot dashboard link:
>>> https://syzkaller.appspot.com/bug?extid=7a1cff37dbbef9e7ba4c
>>>
>>> So far this crash happened 4 times on upstream.
>>>
>>> Unfortunately, I don't have any reproducer for this crash yet.
>>
>> Do you have any of the other traces?  This looks like a something is
>> calling put_pid_ns more than it is calling get_pid_ns causing a
>> reference count mismatch.
>>
>> If this is not: 9ee332d99e4d5a97548943b81c54668450ce641b

Yes, that commit is the trigger. Al wrote patches. Let's check them.

  http://lkml.kernel.org/r/20180402143415.gc30...@zeniv.linux.org.uk
  http://lkml.kernel.org/r/20180403052009.gh30...@zeniv.linux.org.uk

--
struct pid *alloc_pid(struct pid_namespace *ns) {
(...snipped...)
if (unlikely(is_child_reaper(pid))) {
if (pid_ns_prepare_proc(ns)) // ns is freed upon failure.
goto out_free;
}
(...snipped...)
out_free:
spin_lock_irq(_lock);
while (++i <= ns->level) // <= ns is already freed by 
destroy_pid_namespace() explained below.
idr_remove(>idr, (pid->numbers + i)->nr);
(...snipped...)
}
--

--
int pid_ns_prepare_proc(struct pid_namespace *ns) {
  mnt = kern_mount_data(_fs_type, ns) { // <= ns is passed as ns.
mnt = vfs_kern_mount(type, SB_KERNMOUNT, type->name, data) { // <= ns is 
passed as data.
  root = mount_fs(type, SB_KERNMOUNT, name, data) { // <= ns is passed as 
data.
root = type->mount(type, SB_KERNMOUNT, name, data) = // <= ns is passed 
as data.
static struct dentry *proc_mount(struct file_system_type *fs_type, int 
flags, const char *dev_name, void *data) {
  return mount_ns(fs_type, SB_KERNMOUNT, NULL, ns, ns->user_ns, 
proc_fill_super) { // <= ns is passed as ns.
sb = sget_userns(fs_type, ns_test_super, ns_set_super, 
SB_KERNMOUNT, user_ns, ns) { // <= ns is passed as ns.
  err = set(s, data) = // <= ns is passed as data.
  static int ns_set_super(struct super_block *sb, void *data) {
sb->s_fs_info = data; // ns is associated here.
  }
  err = register_shrinker(>s_shrink); // <= fail by fault 
injection.
  deactivate_locked_super(s) {
fs->kill_sb(s) =
static void proc_kill_sb(struct super_block *sb) {
  ns = (struct pid_namespace *)sb->s_fs_info;
  put_pid_ns(ns) { // <= ns is passed as ns
kref_put(>kref, free_pid_ns) { // <= ns refcount 
becomes 0
  destroy_pid_namespace(ns) {
call_rcu(>rcu, delayed_free_pidns) {
  kmem_cache_free(pid_ns_cachep, ns); // <= ns is 
released here after RCU grace period
}
  }
}
  }
}
  }
}
  }
}
  }
}
  }
}
--

>>
>> I could use a few more hints to help narrow down what is going wrong.
>>
>> It would be nice to know what the other 3 crashes looked like and
>> exactly which upstream they were on.
>>
> 
> The other crashes are shown on the syzbot dashboard (link was given in the
> original email).
> 
> Eric
>

Re: KASAN: use-after-free Read in alloc_pid

2018-04-03 Thread Tetsuo Handa 
On 2018/04/03 12:10, Eric Biggers wrote:
> On Mon, Apr 02, 2018 at 06:00:57PM -0500, Eric W. Biederman wrote:
>> syzbot  writes:
>>
>>> Hello,
>>>
>>> syzbot hit the following crash on upstream commit
>>> 9dd2326890d89a5179967c947dab2bab34d7ddee (Fri Mar 30 17:29:47 2018 +)
>>> Merge tag 'ceph-for-4.16-rc8' of git://github.com/ceph/ceph-client
>>> syzbot dashboard link:
>>> https://syzkaller.appspot.com/bug?extid=7a1cff37dbbef9e7ba4c
>>>
>>> So far this crash happened 4 times on upstream.
>>>
>>> Unfortunately, I don't have any reproducer for this crash yet.
>>
>> Do you have any of the other traces?  This looks like a something is
>> calling put_pid_ns more than it is calling get_pid_ns causing a
>> reference count mismatch.
>>
>> If this is not: 9ee332d99e4d5a97548943b81c54668450ce641b

Yes, that commit is the trigger. Al wrote patches. Let's check them.

  http://lkml.kernel.org/r/20180402143415.gc30...@zeniv.linux.org.uk
  http://lkml.kernel.org/r/20180403052009.gh30...@zeniv.linux.org.uk

--
struct pid *alloc_pid(struct pid_namespace *ns) {
(...snipped...)
if (unlikely(is_child_reaper(pid))) {
if (pid_ns_prepare_proc(ns)) // ns is freed upon failure.
goto out_free;
}
(...snipped...)
out_free:
spin_lock_irq(_lock);
while (++i <= ns->level) // <= ns is already freed by 
destroy_pid_namespace() explained below.
idr_remove(>idr, (pid->numbers + i)->nr);
(...snipped...)
}
--

--
int pid_ns_prepare_proc(struct pid_namespace *ns) {
  mnt = kern_mount_data(_fs_type, ns) { // <= ns is passed as ns.
mnt = vfs_kern_mount(type, SB_KERNMOUNT, type->name, data) { // <= ns is 
passed as data.
  root = mount_fs(type, SB_KERNMOUNT, name, data) { // <= ns is passed as 
data.
root = type->mount(type, SB_KERNMOUNT, name, data) = // <= ns is passed 
as data.
static struct dentry *proc_mount(struct file_system_type *fs_type, int 
flags, const char *dev_name, void *data) {
  return mount_ns(fs_type, SB_KERNMOUNT, NULL, ns, ns->user_ns, 
proc_fill_super) { // <= ns is passed as ns.
sb = sget_userns(fs_type, ns_test_super, ns_set_super, 
SB_KERNMOUNT, user_ns, ns) { // <= ns is passed as ns.
  err = set(s, data) = // <= ns is passed as data.
  static int ns_set_super(struct super_block *sb, void *data) {
sb->s_fs_info = data; // ns is associated here.
  }
  err = register_shrinker(>s_shrink); // <= fail by fault 
injection.
  deactivate_locked_super(s) {
fs->kill_sb(s) =
static void proc_kill_sb(struct super_block *sb) {
  ns = (struct pid_namespace *)sb->s_fs_info;
  put_pid_ns(ns) { // <= ns is passed as ns
kref_put(>kref, free_pid_ns) { // <= ns refcount 
becomes 0
  destroy_pid_namespace(ns) {
call_rcu(>rcu, delayed_free_pidns) {
  kmem_cache_free(pid_ns_cachep, ns); // <= ns is 
released here after RCU grace period
}
  }
}
  }
}
  }
}
  }
}
  }
}
  }
}
--

>>
>> I could use a few more hints to help narrow down what is going wrong.
>>
>> It would be nice to know what the other 3 crashes looked like and
>> exactly which upstream they were on.
>>
> 
> The other crashes are shown on the syzbot dashboard (link was given in the
> original email).
> 
> Eric
>

Re: KASAN: use-after-free Read in alloc_pid

2018-04-02 Thread Eric Biggers 
On Mon, Apr 02, 2018 at 06:00:57PM -0500, Eric W. Biederman wrote:
> syzbot  writes:
> 
> > Hello,
> >
> > syzbot hit the following crash on upstream commit
> > 9dd2326890d89a5179967c947dab2bab34d7ddee (Fri Mar 30 17:29:47 2018 +)
> > Merge tag 'ceph-for-4.16-rc8' of git://github.com/ceph/ceph-client
> > syzbot dashboard link:
> > https://syzkaller.appspot.com/bug?extid=7a1cff37dbbef9e7ba4c
> >
> > So far this crash happened 4 times on upstream.
> >
> > Unfortunately, I don't have any reproducer for this crash yet.
> 
> Do you have any of the other traces?  This looks like a something is
> calling put_pid_ns more than it is calling get_pid_ns causing a
> reference count mismatch.
> 
> If this is not: 9ee332d99e4d5a97548943b81c54668450ce641b
> 
> I could use a few more hints to help narrow down what is going wrong.
> 
> It would be nice to know what the other 3 crashes looked like and
> exactly which upstream they were on.
> 

The other crashes are shown on the syzbot dashboard (link was given in the
original email).

Eric

Re: KASAN: use-after-free Read in alloc_pid

2018-04-02 Thread Eric Biggers 
On Mon, Apr 02, 2018 at 06:00:57PM -0500, Eric W. Biederman wrote:
> syzbot  writes:
> 
> > Hello,
> >
> > syzbot hit the following crash on upstream commit
> > 9dd2326890d89a5179967c947dab2bab34d7ddee (Fri Mar 30 17:29:47 2018 +)
> > Merge tag 'ceph-for-4.16-rc8' of git://github.com/ceph/ceph-client
> > syzbot dashboard link:
> > https://syzkaller.appspot.com/bug?extid=7a1cff37dbbef9e7ba4c
> >
> > So far this crash happened 4 times on upstream.
> >
> > Unfortunately, I don't have any reproducer for this crash yet.
> 
> Do you have any of the other traces?  This looks like a something is
> calling put_pid_ns more than it is calling get_pid_ns causing a
> reference count mismatch.
> 
> If this is not: 9ee332d99e4d5a97548943b81c54668450ce641b
> 
> I could use a few more hints to help narrow down what is going wrong.
> 
> It would be nice to know what the other 3 crashes looked like and
> exactly which upstream they were on.
> 

The other crashes are shown on the syzbot dashboard (link was given in the
original email).

Eric

Re: KASAN: use-after-free Read in alloc_pid

2018-04-02 Thread Eric W. Biederman 
syzbot  writes:

> Hello,
>
> syzbot hit the following crash on upstream commit
> 9dd2326890d89a5179967c947dab2bab34d7ddee (Fri Mar 30 17:29:47 2018 +)
> Merge tag 'ceph-for-4.16-rc8' of git://github.com/ceph/ceph-client
> syzbot dashboard link:
> https://syzkaller.appspot.com/bug?extid=7a1cff37dbbef9e7ba4c
>
> So far this crash happened 4 times on upstream.
>
> Unfortunately, I don't have any reproducer for this crash yet.

Do you have any of the other traces?  This looks like a something is
calling put_pid_ns more than it is calling get_pid_ns causing a
reference count mismatch.

If this is not: 9ee332d99e4d5a97548943b81c54668450ce641b

I could use a few more hints to help narrow down what is going wrong.

It would be nice to know what the other 3 crashes looked like and
exactly which upstream they were on.

Eric

Re: KASAN: use-after-free Read in alloc_pid

2018-04-02 Thread Eric W. Biederman 
syzbot  writes:

> Hello,
>
> syzbot hit the following crash on upstream commit
> 9dd2326890d89a5179967c947dab2bab34d7ddee (Fri Mar 30 17:29:47 2018 +)
> Merge tag 'ceph-for-4.16-rc8' of git://github.com/ceph/ceph-client
> syzbot dashboard link:
> https://syzkaller.appspot.com/bug?extid=7a1cff37dbbef9e7ba4c
>
> So far this crash happened 4 times on upstream.
>
> Unfortunately, I don't have any reproducer for this crash yet.

Do you have any of the other traces?  This looks like a something is
calling put_pid_ns more than it is calling get_pid_ns causing a
reference count mismatch.

If this is not: 9ee332d99e4d5a97548943b81c54668450ce641b

I could use a few more hints to help narrow down what is going wrong.

It would be nice to know what the other 3 crashes looked like and
exactly which upstream they were on.

Eric

KASAN: use-after-free Read in alloc_pid

2018-04-01 Thread syzbot 

Hello,

syzbot hit the following crash on upstream commit
9dd2326890d89a5179967c947dab2bab34d7ddee (Fri Mar 30 17:29:47 2018 +)
Merge tag 'ceph-for-4.16-rc8' of git://github.com/ceph/ceph-client
syzbot dashboard link:  
https://syzkaller.appspot.com/bug?extid=7a1cff37dbbef9e7ba4c


So far this crash happened 4 times on upstream.
Unfortunately, I don't have any reproducer for this crash yet.
Raw console output:  
https://syzkaller.appspot.com/x/log.txt?id=6588786309857280
Kernel config:  
https://syzkaller.appspot.com/x/.config?id=-2760467897697295172

compiler: gcc (GCC) 7.1.1 20170620

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+7a1cff37dbbef9e7b...@syzkaller.appspotmail.com
It will help syzbot understand when the bug is fixed. See footer for  
details.

If you forward the report, please keep this part and the footer.

R10: 2900 R11: 0246 R12: 0015
R13: 0051 R14: 006f2838 R15: 0028
==
BUG: KASAN: use-after-free in alloc_pid+0x9a6/0xa00 kernel/pid.c:236
Read of size 4 at addr 8801b56d0088 by task syz-executor4/3533

CPU: 1 PID: 3533 Comm: syz-executor4 Not tainted 4.16.0-rc7+ #372
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS  
Google 01/01/2011

Call Trace:
 __dump_stack lib/dump_stack.c:17 [inline]
 dump_stack+0x194/0x24d lib/dump_stack.c:53
 print_address_description+0x73/0x250 mm/kasan/report.c:256
 kasan_report_error mm/kasan/report.c:354 [inline]
 kasan_report+0x23c/0x360 mm/kasan/report.c:412
 __asan_report_load4_noabort+0x14/0x20 mm/kasan/report.c:432
 alloc_pid+0x9a6/0xa00 kernel/pid.c:236
 copy_process.part.38+0x2516/0x4bd0 kernel/fork.c:1807
 copy_process kernel/fork.c:1606 [inline]
 _do_fork+0x1f7/0xf70 kernel/fork.c:2087
 SYSC_clone kernel/fork.c:2194 [inline]
 SyS_clone+0x37/0x50 kernel/fork.c:2188
 do_syscall_64+0x281/0x940 arch/x86/entry/common.c:287
 entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x454e79
RSP: 002b:7f6165b9ac68 EFLAGS: 0246 ORIG_RAX: 0038
RAX: ffda RBX: 7f6165b9b6d4 RCX: 00454e79
RDX: 28c0 RSI: 2800 RDI: 2000c100
RBP: 0072bea0 R08: 2940 R09: 
R10: 2900 R11: 0246 R12: 0015
R13: 0051 R14: 006f2838 R15: 0028

Allocated by task 3533:
 save_stack+0x43/0xd0 mm/kasan/kasan.c:447
 set_track mm/kasan/kasan.c:459 [inline]
 kasan_kmalloc+0xad/0xe0 mm/kasan/kasan.c:552
 kasan_slab_alloc+0x12/0x20 mm/kasan/kasan.c:489
 kmem_cache_alloc+0x12e/0x760 mm/slab.c:3542
 kmem_cache_zalloc include/linux/slab.h:691 [inline]
 create_pid_namespace kernel/pid_namespace.c:116 [inline]
 copy_pid_ns+0x257/0xc60 kernel/pid_namespace.c:175
 create_new_namespaces+0x307/0x880 kernel/nsproxy.c:94
 copy_namespaces+0x340/0x400 kernel/nsproxy.c:165
 copy_process.part.38+0x2380/0x4bd0 kernel/fork.c:1796
 copy_process kernel/fork.c:1606 [inline]
 _do_fork+0x1f7/0xf70 kernel/fork.c:2087
 SYSC_clone kernel/fork.c:2194 [inline]
 SyS_clone+0x37/0x50 kernel/fork.c:2188
 do_syscall_64+0x281/0x940 arch/x86/entry/common.c:287
 entry_SYSCALL_64_after_hwframe+0x42/0xb7

Freed by task 3539:
 save_stack+0x43/0xd0 mm/kasan/kasan.c:447
 set_track mm/kasan/kasan.c:459 [inline]
 __kasan_slab_free+0x11a/0x170 mm/kasan/kasan.c:520
 kasan_slab_free+0xe/0x10 mm/kasan/kasan.c:527
 __cache_free mm/slab.c:3486 [inline]
 kmem_cache_free+0x83/0x2a0 mm/slab.c:3744
 delayed_free_pidns+0x82/0xb0 kernel/pid_namespace.c:157
 __rcu_reclaim kernel/rcu/rcu.h:172 [inline]
 rcu_do_batch kernel/rcu/tree.c:2674 [inline]
 invoke_rcu_callbacks kernel/rcu/tree.c:2933 [inline]
 __rcu_process_callbacks kernel/rcu/tree.c:2900 [inline]
 rcu_process_callbacks+0xd6c/0x17f0 kernel/rcu/tree.c:2917
 __do_softirq+0x2d7/0xb85 kernel/softirq.c:285

The buggy address belongs to the object at 8801b56d0040
 which belongs to the cache pid_namespace of size 240
The buggy address is located 72 bytes inside of
 240-byte region [8801b56d0040, 8801b56d0130)
The buggy address belongs to the page:
page:ea0006d5b400 count:1 mapcount:0 mapping:8801b56d0040 index:0x0
flags: 0x2fffc000100(slab)
raw: 02fffc000100 8801b56d0040  0001000d
raw: ea00074458a0 ea00073389e0 8801d40b2c00 
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 8801b56cff80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 8801b56d: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb

8801b56d0080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb

  ^
 8801b56d0100: fb fb fb fb fb fb fc fc fc fc fc fc fc fc fb fb
 8801b56d0180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==


---
This bug

KASAN: use-after-free Read in alloc_pid

2018-04-01 Thread syzbot 

Hello,

syzbot hit the following crash on upstream commit
9dd2326890d89a5179967c947dab2bab34d7ddee (Fri Mar 30 17:29:47 2018 +)
Merge tag 'ceph-for-4.16-rc8' of git://github.com/ceph/ceph-client
syzbot dashboard link:  
https://syzkaller.appspot.com/bug?extid=7a1cff37dbbef9e7ba4c


So far this crash happened 4 times on upstream.
Unfortunately, I don't have any reproducer for this crash yet.
Raw console output:  
https://syzkaller.appspot.com/x/log.txt?id=6588786309857280
Kernel config:  
https://syzkaller.appspot.com/x/.config?id=-2760467897697295172

compiler: gcc (GCC) 7.1.1 20170620

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+7a1cff37dbbef9e7b...@syzkaller.appspotmail.com
It will help syzbot understand when the bug is fixed. See footer for  
details.

If you forward the report, please keep this part and the footer.

R10: 2900 R11: 0246 R12: 0015
R13: 0051 R14: 006f2838 R15: 0028
==
BUG: KASAN: use-after-free in alloc_pid+0x9a6/0xa00 kernel/pid.c:236
Read of size 4 at addr 8801b56d0088 by task syz-executor4/3533

CPU: 1 PID: 3533 Comm: syz-executor4 Not tainted 4.16.0-rc7+ #372
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS  
Google 01/01/2011

Call Trace:
 __dump_stack lib/dump_stack.c:17 [inline]
 dump_stack+0x194/0x24d lib/dump_stack.c:53
 print_address_description+0x73/0x250 mm/kasan/report.c:256
 kasan_report_error mm/kasan/report.c:354 [inline]
 kasan_report+0x23c/0x360 mm/kasan/report.c:412
 __asan_report_load4_noabort+0x14/0x20 mm/kasan/report.c:432
 alloc_pid+0x9a6/0xa00 kernel/pid.c:236
 copy_process.part.38+0x2516/0x4bd0 kernel/fork.c:1807
 copy_process kernel/fork.c:1606 [inline]
 _do_fork+0x1f7/0xf70 kernel/fork.c:2087
 SYSC_clone kernel/fork.c:2194 [inline]
 SyS_clone+0x37/0x50 kernel/fork.c:2188
 do_syscall_64+0x281/0x940 arch/x86/entry/common.c:287
 entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x454e79
RSP: 002b:7f6165b9ac68 EFLAGS: 0246 ORIG_RAX: 0038
RAX: ffda RBX: 7f6165b9b6d4 RCX: 00454e79
RDX: 28c0 RSI: 2800 RDI: 2000c100
RBP: 0072bea0 R08: 2940 R09: 
R10: 2900 R11: 0246 R12: 0015
R13: 0051 R14: 006f2838 R15: 0028

Allocated by task 3533:
 save_stack+0x43/0xd0 mm/kasan/kasan.c:447
 set_track mm/kasan/kasan.c:459 [inline]
 kasan_kmalloc+0xad/0xe0 mm/kasan/kasan.c:552
 kasan_slab_alloc+0x12/0x20 mm/kasan/kasan.c:489
 kmem_cache_alloc+0x12e/0x760 mm/slab.c:3542
 kmem_cache_zalloc include/linux/slab.h:691 [inline]
 create_pid_namespace kernel/pid_namespace.c:116 [inline]
 copy_pid_ns+0x257/0xc60 kernel/pid_namespace.c:175
 create_new_namespaces+0x307/0x880 kernel/nsproxy.c:94
 copy_namespaces+0x340/0x400 kernel/nsproxy.c:165
 copy_process.part.38+0x2380/0x4bd0 kernel/fork.c:1796
 copy_process kernel/fork.c:1606 [inline]
 _do_fork+0x1f7/0xf70 kernel/fork.c:2087
 SYSC_clone kernel/fork.c:2194 [inline]
 SyS_clone+0x37/0x50 kernel/fork.c:2188
 do_syscall_64+0x281/0x940 arch/x86/entry/common.c:287
 entry_SYSCALL_64_after_hwframe+0x42/0xb7

Freed by task 3539:
 save_stack+0x43/0xd0 mm/kasan/kasan.c:447
 set_track mm/kasan/kasan.c:459 [inline]
 __kasan_slab_free+0x11a/0x170 mm/kasan/kasan.c:520
 kasan_slab_free+0xe/0x10 mm/kasan/kasan.c:527
 __cache_free mm/slab.c:3486 [inline]
 kmem_cache_free+0x83/0x2a0 mm/slab.c:3744
 delayed_free_pidns+0x82/0xb0 kernel/pid_namespace.c:157
 __rcu_reclaim kernel/rcu/rcu.h:172 [inline]
 rcu_do_batch kernel/rcu/tree.c:2674 [inline]
 invoke_rcu_callbacks kernel/rcu/tree.c:2933 [inline]
 __rcu_process_callbacks kernel/rcu/tree.c:2900 [inline]
 rcu_process_callbacks+0xd6c/0x17f0 kernel/rcu/tree.c:2917
 __do_softirq+0x2d7/0xb85 kernel/softirq.c:285

The buggy address belongs to the object at 8801b56d0040
 which belongs to the cache pid_namespace of size 240
The buggy address is located 72 bytes inside of
 240-byte region [8801b56d0040, 8801b56d0130)
The buggy address belongs to the page:
page:ea0006d5b400 count:1 mapcount:0 mapping:8801b56d0040 index:0x0
flags: 0x2fffc000100(slab)
raw: 02fffc000100 8801b56d0040  0001000d
raw: ea00074458a0 ea00073389e0 8801d40b2c00 
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 8801b56cff80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 8801b56d: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb

8801b56d0080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb

  ^
 8801b56d0100: fb fb fb fb fb fb fc fc fc fc fc fc fc fc fb fb
 8801b56d0180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==


---
This bug